Chapter 6 - Weather and Seasons

Unit C - The Sky

Chapter 6 - Weather and the Seasons

On July 4, 1999, a rare and terrifying storm swept through the Boundary Waters Canoe Area Wilderness in northern Minnesota. What began like a standard-issue thunderstorm soon turned strange and fierce, generating green clouds and strong winds reminiscent of a tornado. In fact, the storm was a cousin of the tornado: a derecho (pronounced "de-RAY-cho"), a type of storm so infrequent and fast-moving that only in recent years have meteorologists begun to understand how to recognize and forecast it